This research program is aimed at the understanding of the interaction of viral and cellular functions which determines the altered phenotype of cells transformed by DNA tumor viruses, and some of the parameters which differentiate transformed from normal cells. The project consists of 5 parts, which are listed below: 1) The study of the regulation of viral functions in SV40 or polyoma transformed cells, particularly of the integration and transcription of the viral DNA. 2) The study of the Sv40 specific membrane antigens and their relationship to nuclear T-antigen(s). 3) The study of the early events in SV40 infection, with particular regard to integration. 4) The study of the cellular functions required for Herpes virus DNA replication and integration. This project will take advantage of the use of temperature sensitive (ts) cell mutants with specific growth defects. 5) The study of the role of RNA unwinding protein(s), in m-RNP binding to ribosomes and m-RNA trnasport through the nuclear membrane in eukaryotes.